SBIR-STTR Award

Ceramic polymers or "geopolymers" are amorphous to semi-crystalline three dimensional alumino-silicate materials resulting from geochemistry. "Geopolymerisation" is the chemical reaction between various aluminosilicate oxides (Al+3 in Iv, V, or Vi fold coordination) with silicates under highly alkaline conditions, yielding polymeric Si-O-Al-O bonds (HUA & VanDeventer 1999). Geopolymers form co-polymerisation of individual alumino and silicate species, which originate from materials containing host sources of either silicon, aluminum or combinations of the foregoing. In order to form geopolymer chains, rings or complete tetrahedral, positive ions such as K, Na, Ca, Ba, Nhy, H30 (etc) must be present in the framework in order to balance the negative charge of Al. Differing chain and ring structures form at different Si: Al ratios. Polymeric structures are generally formed when the Si:Al ratio is greater than 3. From this polysilicate chains can form 3-dimensional cross-linked structures. It is this cross-linking phenomenon which facilitates the ability to enhance the standard characteristics of traditional ceramics yielding ceramic polymers (geopolymers)which are characterized by

Keywords:
Ceramic, Polymer, Geopolymerization, Alumino-Silicate, Durability, Stability, Transformation, Toughening

Geopolymer cements (GPs) possess the ability to quickly form high-strength, thermally-stable, and near-net shape structures at room temperature. Their chemical nature enables them to bond strongly to both metal and ceramic parts acting as refractory glue. Through our work in the Phase I STTR, a detailed understanding of the basic chemistry, structure, processing conditions, thermal behavior, and composite manufacturing has been gained. Phase II will extend upon this knowledge in a few promising application areas. Low cost GP molds were already shown to function well in the field as a method to solidify near-net shape molten metal parts. Improvements to the material design will now focus on material durability over multiple cycles. By tailoring chemistry and heating, one can use GPs to produce a variety of crystalline phases of defined properties as well as high strength ceramic matrix composites (CMC). The use of GPs to bond ceramic and metal parts will also be further explored in more detail in relation to commercialization potential.

Keywords:
Heat Tolerant, High Strength, Ceramic, Durability, Multiple Cycles, Transformation, Stability